EP0720845A1 - Cosmetic composition in form of a supple poste and preparation process - Google Patents

Abstract

In a cosmetic compsn. in the form of a soft paste, there is a fatty phase contg. waxes, at least 95% of which have an initial m. pt. of at least 50 degrees C. Waxes form 10-60 (15-35) wt.% of the compsn., and 100% of the waxes have initial m.pt. above 50 (above 65) deg.C. Claimed waxes are carnauba wax, polyethylene wax and 'Tisco Wax 88' (RTM: microcrystalline wax). Fatty phase contains oils, comprising e.g. paraffin oil, vaseline, perhydrosqualene, sweet almond oil etc. forming 40-90% (65-85%) of the compsn. Compsn. may contain a dye powder e.g. carbon black, oxide of Cr or of Fe, an ultramarine, Mn pyrophosphate, ferric blue, TiO2, nacreous agent or organic dye, and mineral or organic powder fillers (e.g. talc, mica etc.).

Description

The present invention relates to a composition in the form of a flexible paste, in particular a cosmetic composition which can be used for making up the lips, or as a composition for treating the skin and / or the lips.

Cosmetic compositions which can be applied to the lips as a care or make-up product, such as lipsticks, generally contain fatty substances and waxes, and optionally additives and pigments.
In particular, such compositions are known, which are in the form of a flexible paste, capable of being applied after removal using an applicator, for example a brush.
These compositions can contain waxes which gives them remarkable qualities of consistency, smoothness and hold of the applied film.
In order to introduce relatively large quantities of waxes into these compositions, a preparation process has been proposed which consists in preparing the mixture of constituents, in heating it to a temperature at which the waxes are at least partially melted, then in subject it to a mixing operation during at least part of its cooling.
There is thus a crystallization of the waxes in a form which makes it possible to obtain a flexible and easily removable paste.
However, it has been found that certain waxes do not make it possible to obtain a cosmetic composition having optimal and constant cosmetic qualities during their conservation, in particular when this conservation was carried out, even partially, at a temperature above a usual temperature of l '' around 20-25 ° C.
In fact, depending on the nature of the waxes present in the composition, it has been found in certain cases, a modification of the viscosity of said composition, which can cause significant hardening of the composition and difficulties in application.

The aim of the present invention is to overcome these drawbacks and to propose a cosmetic composition having optimal cosmetic qualities throughout its storage, inter alia a viscosity almost constant over time, whatever the temperature or the temperature changes. suffered.

An object of the present invention is therefore a cosmetic composition in the form of a flexible paste and comprising a fatty phase in which one or more waxes are present, said composition being characterized in that at least 95% of said waxes have a starting melting point greater than or equal to 50 ° C.

Another object of the invention is a process for the preparation of such a cosmetic composition, in which the temperature is brought to which the waxes melt at least partially, at least part of the various constituents of the composition, including the waxes, the rest of the constituents are added where appropriate, then the mixture obtained is kneaded during at least part of its cooling.

The present invention makes it possible to obtain compositions which remain stable over time, that is to say the viscosity of which remains almost constant. These compositions have an original flexible texture and exhibit, after application, good hold and good gloss.

The composition according to the invention therefore comprises a fatty phase in which one or more waxes may be present, at least 95% of said waxes having to have a starting melting point greater than or equal to 50 ° C.

By "starting melting temperature" in the present description is meant the temperature at which a wax begins to melt.
This temperature can be determined by ATD (differential thermal analysis) which makes it possible to obtain the thermogram (or melting curve) of the wax considered. The starting melting point corresponds to the temperature at which a notable change in slope can be observed in the thermogram. The melting point, meanwhile, represents the minimum point of said thermogram.

Without being bound by the present explanation, it can be assumed that the change in viscosity observed during the storage of certain cosmetic compositions is linked to the modification of the form in which the waxes crystallize.
In fact, during the manufacture of the composition, the waxes are crystallized in a certain shape which will make it possible to obtain a flexible paste.
During a significant rise in temperature during their storage, said waxes can melt at least partially, then recrystallize in a form different from the initial crystalline form, this second form no longer making it possible to obtain a flexible paste but which can lead to a paste of greater viscosity and therefore of a more rigid consistency.
Thus, by choosing at least 95% of the waxes present in the composition from among the waxes having a starting melting temperature greater than or equal to 50 ° C., it is possible to obtain a composition whose viscosity remains constant. Preferably, waxes are used whose starting melting temperature is greater than 65 ° C and / or 100% waxes are used whose starting melting temperature is greater than or equal to 50 ° C.

The waxes capable of being used in the present invention, that is to say making it possible to maintain a viscosity of the cosmetic composition constant, can be of any kind, in particular of mineral, animal, vegetable or synthetic origin.

Mention may mainly be made of Carnauba wax, certain polyethylene waxes and certain microcrystalline waxes such as that sold by Tisco under the name "Tisco Wax 88".
These waxes can be used alone or as a mixture.
They can also be used in admixture with waxes whose starting melting point is less than 50 ° C, since these second waxes cannot represent more than 5% by weight of the totality of the waxes.

The composition according to the invention can comprise in total 10-60% by weight of waxes relative to the final weight of the composition, preferably 15-35%.

• . les huiles minérales telles que l'huile de paraffine ou de vaseline,
• . les huiles animales telles que le perhydrosqualène ou l'huile d'arara,
• . les huiles végétales telles que l'huile d'amande douce, de calophyllum, de palme, de ricin, d'avocat, de jojoba, doive ou de germes de céréales,
• . des esters d'acide lanolique, d'acide oléique, d'acide laurique, d'acide stéarique ou d'acide myristique par exemple,
• . des alcools tels que l'alcool oléique, l'alcool linoléique ou linolénique, l'alcool isostéarique ou l'octyl dodécanol,
• . des acétylglycérides, des octanoates, décanoates ou ricinoléates d'alcools ou de polyalcools.

Ces constituants gras peuvent représenter 40-90% en poids de la composition, de préférence 65-85%.The fatty phase can also comprise other fatty constituents such as oils. We can in particular quote:

• . mineral oils such as paraffin oil or petroleum jelly,
• . animal oils such as perhydrosqualene or arara oil,
• . vegetable oils such as sweet almond oil, calophyllum oil, palm oil, castor oil, avocado oil, jojoba oil, doive or cereal germs,
• . esters of lanolic acid, oleic acid, lauric acid, stearic acid or myristic acid for example,
• . alcohols such as oleic alcohol, linoleic or linolenic alcohol, isostearic alcohol or octyl dodecanol,
• . acetylglycerides, octanoates, decanoates or ricinoleates of alcohols or polyalcohols.

These fatty constituents can represent 40-90% by weight of the composition, preferably 65-85%.

In known manner, it is possible to add to the composition according to the invention a pulverulent coloring agent such as carbon black, chromium or iron oxides, ultramarines, manganese pyrophosphate, ferric blue, titanium dioxide , pearlescent agents generally used in admixture with colored pigments or certain organic dyes generally used in admixture with colored pigments and commonly used in the cosmetic industry.
These coloring agents can be present in an amount of 0 to 20%.

It is also possible to add mineral or organic powder fillers, generally in an amount of 0 to 40%.
These pulverulent fillers can be chosen from talc, micas, kaolin, zinc or titanium oxides, calcium or magnesium carbonates, silica, spherical titanium dioxide, glass and ceramic beads, metallic soaps derived from carboxylic acids having 8-22 carbon atoms, powders of unexpanded synthetic polymers, expanded powders and powders of natural organic compounds such as cereal starches, crosslinked or not.

It is also possible to add any additive commonly used in the cosmetic industry, such as antioxidants, perfumes, preservatives, as well as cosmetic and / or pharmaceutical active agents such as vitamin derivatives, essential fatty acids, sphingocerils, liposoluble sunscreens, anti-inflammatories or oily plant extracts, or even liposoluble polymers, and / or silicone oils and / or gums such as dimethylpolysiloxanes. These additives can be present at a rate of 0-10% by weight.

In order to prepare the composition according to the invention, it is possible first of all to prepare a premix comprising at least part of the various constituents of the composition, including at least the wax according to the invention, heating this premix to a temperature at which said wax melts at least partially, add the rest of the constituents if necessary, then knead the mixture obtained during at least part of its cooling down to room temperature.
It has in fact been found that when the mixture is kneaded during at least part of its cooling, so as to create shear zones, a composition is obtained which is in the form of a homogeneous and flexible paste. It would seem, without however being bound by this explanation, that under these conditions the wax crystallizes in the form of fine crystals, which would explain why the composition remains in the form of a flexible paste.

The heating operation can be carried out according to any known technique.
The kneading operation can be carried out, for example, in a roller mill having two cylinders rotating in opposite directions between which the dough passes, or in a mixer-extruder which makes it possible to obtain a dough of very constant quality so reproducible. In addition, it is possible, by adapting the proud outlet of the mixer-extruder, to condition the composition in line at the outlet of said die.
In a particular embodiment of the invention, the operations of mixing, heating and / or kneading / shearing, or even cooling, are carried out in one or more extruders arranged one after the other, preferably in a single twin screw extruder.
Indeed, the composition obtained after extrusion has a particular softness, and provides a certain feeling of slippery when applied to the skin, while avoiding the appearance and sensation of oily fat.
The conditions under which the extrusion can be carried out are described in patent application FR94-00756, the content of which is incorporated into the present application by reference.

A composition for topical use is thus obtained, which can be applied to the skin and / or the lips as a makeup product, lipstick for example, or as a care product.

The composition is in the form of a flexible paste, the viscosity of which can be measured, as opposed to the solid structure of a stick, or stick, the viscosity of which cannot be measured. Said dynamic viscosity at 25 ° C is generally between 3 and 35 Pa.s, measured with a CONTRAVES TV rotary viscometer equipped with a mobile "MS-r4" at a frequency of 60 Hz.

The invention is illustrated in more detail in the following examples, in which the percentages are given by weight.
The viscosity measurements are carried out at 25 ° C., using a Contraves rotary viscometer equipped with an MS-R4 mobile.
The measurements of the melting characteristics of the waxes are made by ATD (differential thermal analysis) under the following conditions: heating from 25 to 110 ° C., at a speed of 1 ° C./minute.

Example 1 : Composition according to the invention

A lipstick having the following composition is prepared: . petroleum jelly oil 22.5% . lanolin oil 23.5% . isopropyl lanolate 24% . microcrystalline wax (non-polar mineral wax sold by Tisco, under the name "Tisco wax 88") 20% . fillers (titanium oxide, mica) 3.5% . pigments 6.5%

• . température d'entrée : 100°C
• . température de sortie : 30°C
• . temps de résidence : 3 minutes environ
• . vitesse des vis : 350 tours/min

On obtient en sortie une pâte souple, se présentant sous forme d'une seule phase stable et homogène, et pouvant être prélevée à l'aide d'un pinceau pour son application.
Après application, cette pâte est considérée comme présentant des qualités de douceur et de glissant satisfaisantes et ne présente pas de texture huileuse.These various ingredients are mixed at approximately 100 ° C. and the mixture is introduced at the top of a twin-screw extruder.
The extrusion is carried out under the following conditions:

• . inlet temperature: 100 ° C
• . outlet temperature: 30 ° C
• . residence time: about 3 minutes
• . screw speed: 350 rpm

A flexible paste is obtained at the outlet, in the form of a single stable and homogeneous phase, which can be removed using a brush for its application.
After application, this paste is considered to have satisfactory qualities of softness and slipperiness and does not have an oily texture.

• . conservation à 25°C : 90 poises (9 Pa.s)
• . conservation à 47°C : 92 poises (9,2 Pa.s)

On constate donc que la composition selon l'invention conserve quasiment la même viscosité après conservation à température ambiante ou à température élevée.
Après six mois de conservation à 47°C, la pâte n'a pas changé d'aspect et peut toujours être prélevée à l'aide d'un pinceau pour être appliquée sur la peau. La cire utilisée dans cette composition possède une température de fusion commençante de l'ordre de 65-70°C et un point de fusion à 91-93°C environ.After six months of storage, at 25 ° C and 47 ° C, the following viscosity measurements are obtained:

• . storage at 25 ° C: 90 poises (9 Pa.s)
• . storage at 47 ° C: 92 poises (9.2 Pa.s)

It is therefore found that the composition according to the invention retains almost the same viscosity after storage at room temperature or at elevated temperature.
After six months of storage at 47 ° C, the paste has not changed in appearance and can still be removed with a brush to be applied to the skin. The wax used in this composition has a starting melting temperature of the order of 65-70 ° C and a melting point of approximately 91-93 ° C.

Example 2 : Comparative example

A lipstick having the following composition is prepared: . petroleum jelly oil 22.5% . lanolin oil 23.5% . isopropyl lanolate 24% . microcrystalline wax (non-polar mineral wax sold by RMC, under the name of “Feruwax 30540”) 20% . fillers (titanium oxide, mica) 3.5% . pigments 6.5%

The lipstick is prepared in the same manner as in Example 1, and a flexible paste can also be obtained which can be removed using a brush.

• . conservation à 25°C : 80 poises (8 Pa.s)
• . conservation à 47°C : 175 poises (17,5 Pa.s)

On constate donc qu'après deux mois seulement de conservation à 47°C, on obtient une composition très épaissie, qui ne peut plus sortir de l'applicateur. La cire utilisée, bien qu'ayant un point de fusion à environ 69-71°C, a une température de fusion commençante de l'ordre de 45-46°C.
Ainsi, le simple fait de choisir une cire dont le point de fusion est de l'ordre de la température de conservation n'est pas suffisant en soi pour permettre de garder une viscosité constante à la composition et donc de ses propriétés cosmétiques convenables.After storage for two months, the following viscosity measurements are obtained:

• . storage at 25 ° C: 80 poises (8 Pa.s)
• . storage at 47 ° C: 175 poises (17.5 Pa.s)

It is therefore found that after only two months of storage at 47 ° C., a very thickened composition is obtained, which can no longer leave the applicator. The wax used, although having a melting point at around 69-71 ° C, has a starting melting temperature of the order of 45-46 ° C.
Thus, the simple fact of choosing a wax whose melting point is of the order of the storage temperature is not in itself sufficient to allow the viscosity of the composition to be kept constant and therefore of its suitable cosmetic properties.

Claims (15)

Cosmetic composition in the form of a flexible paste and comprising a fatty phase in which one or more waxes are present, characterized in that at least 95% of said waxes have a starting melting point greater than or equal to 50 ° C. . A composition according to claim 1, wherein 100% of the waxes have a starting melting temperature above 50 ° C. Composition according to one of the preceding claims, in which the waxes have a starting melting point above 65 ° C. Composition according to one of the preceding claims, in which the waxes are chosen from Carnauba wax, certain polyethylene waxes and certain microcrystalline waxes such as that sold by Tisco under the name "Tisco Wax 88". Composition according to one of the preceding claims, in which the waxes represent 10-60%, preferably 15-35%, by weight of the composition. Composition according to one of the preceding claims, in which the fatty phase also comprises other fatty constituents chosen from oils. Composition according to Claim 6, in which the other fatty constituents are chosen from paraffin or petrolatum oil, perhydrosqualene or arara oil, sweet almond oil, calophyllum oil, palm oil, castor oil , avocado, jojoba, olive or germ of cereals, esters of lanolic acid, oleic acid, lauric acid, stearic acid or myristic acid, alcohols such as oleic alcohol, linoleic or linolenic alcohol, isostearic alcohol or octyl dodecanol, acetylglycerides, octanoates, decanoates or ricinoleates of alcohols or polyalcohols. Composition according to one of Claims 6 to 7, in which the other fatty constituents represent 40-90%, preferably 65-85%, by weight of the composition. Composition according to one of the preceding claims, further comprising a pulverulent coloring agent such as carbon black, chromium or iron oxides, ultramarines, manganese pyrophosphate, ferric blue, titanium dioxide, pearlescent agents and certain organic dyes. Composition according to one of the preceding claims, further comprising mineral or organic powder fillers, such as talc, micas, kaolin, zinc or titanium oxides, calcium or magnesium carbonates, silica, spherical titanium dioxide, glass and ceramic beads, metallic soaps derived from carboxylic acids having 8-22 carbon atoms, powders of unexpanded synthetic polymers, expanded powders and powders of natural organic compounds such as cereal starches, crosslinked or not. Composition according to one of the preceding claims, which is in the form of a makeup and / or lip care product. Process for the preparation of a composition in the form of a flexible paste and comprising a fatty phase in which one or more waxes are present, 95% of said waxes having a starting melting temperature greater than or equal to 50 ° C, in which at least part of the various constituents of the composition, including the waxes, are brought to a temperature at which the waxes at least partially melt, the rest of the constituents are added where appropriate, then the mixture obtained is kneaded for at least one part of its cooling. The method of claim 12, wherein the kneading operation is carried out in a roller mill or in an extruder. Process according to any one of Claims 12 to 13, in which the mixing, heating and / or kneading operations are carried out in one or more extruders arranged one after the other. Method according to one of Claims 12 to 14, in which the mixing, heating and kneading operations are carried out in a single twin-screw extruder.